ARM: uniphier: dts: sync with Linux 4.20

Currently, the DWC3 USB node is out of sync because the bindings
for the UniPhier DWC3 PHY diverged between Linux and U-Boot.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/arch/arm/dts/uniphier-ld20-ref.dts b/arch/arm/dts/uniphier-ld20-ref.dts
index 440c2e6..406244a 100644
--- a/arch/arm/dts/uniphier-ld20-ref.dts
+++ b/arch/arm/dts/uniphier-ld20-ref.dts
@@ -75,3 +75,7 @@
 		drive-strength = <9>;
 	};
 };
+
+&usb {
+	status = "okay";
+};